“From prehistory to the present with many episodes in between, the region has a surprisingly meaty history of humans eating humans.”
I’m not sure if this is news as people have been doubting the blood eagle for decades, but it does a nice summary of the reasons the evidence makes it look like a later invention.
I’m not convinced there is a single origin. There were at least three outlaws named Robin or Robert between the Norman invasion and 1100. There is a long history of outlaw stories and a long history of aristocratic outlaws and guerrilla warfare stretching through the whole Medieval period. My belief is that common people liked to hear stories about people tricking nobles and nobles liked stories about patriots fighting invaders. A wide variety of outlaw stories, some political and some not were likely circulating for centuries. I’m willing to bet this William is one of them along with a huge bunch that accreted in the 14th century during a period of particularly intense outlawry early in the centenary. I suspect that over time, the “Robin Hood” brand was a good way to get paid to tell or sing stories of this type and for a local village storyteller, Robin hood stories were good for a pint. It was simpler to take stories about this sort of outlawry and/or guerrilla warfare and change the names to fit with the developing mythos. I’m not convinced that there is any one origin for the stories, but rather a gathering of stories of a type under one set of names. I am very willing to think this particular bandit was a major contributor of elements and stories to that mythos, but I don’t think it’s provable that he is the one true source even if he was actually the origin. Some things aren’t knowable.
I know if they actually find them, there’d likely be no soft tissue, but I’d be fascinated to see if they could find signs of what killed him, as you can sometimes tell disease and the like from bones. However I suspect even if they find bones they’ll have a hard time authenticating them.